Method of burning liquid fuel



OC. 20,1936. B; H LUNDBQRG ET AL l 2,058,089

` METHOD OF BURNING LIQUID FUEL Filed 00T.. 13, 1955 3 Sheets-Sheet 1 mmwww.. |m.. 1|

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Oct. 20, 1936. B. H. L UNDEsc'DRG ET A1. 2,058,085

METHOD oF BURNING LIQUID FUEL A Filed uw. 13, 1953 s sheets-sheet `2Oct. 20, 1936. B. H. LUNDBORG ET A1. -2,058,089

.METHOD BURNING LIQUID` FUEL A Filed Oct. l5, 1953 5 Sheets-Sheet; 5

Patented Get. 20, 1936 f UNITED sTA'lA-Es PATENT OFFICE METHOD F BURNINGLIQUID FUEL Application October 13, 1933, Serial No. 693,516 In SwedenNovember 17, 1931 8 Claims.

When firing with liquidfuel at or in the neighbourhood of atmosphericpressure, thefuel Was hitherto continuously fed into the furnace throughsuitablenozzles.

The spreading and mixing of the fuel with the necessary air ofcombustionlwas, as a -rule, Vaccomplished by giving the fuel a certainvelocity or a rotar-y motion by means/of a centrifugal. sprayer N or `byuseof compressed air,istea1`n or in some 10 other Way,y so asto effect avgood mixture of the fuel with air before the combustion. i i -In such acontinuous fuel supply it has, however, proved diicult to obtain asatisfactory-combus-tion of minor-fuel `quantitiesper time unit. Smallerquantities'than about V5kg-oil per hour could not, with safety, becomb-ustedin a4 reliable and regular manner, -although in minor heatingplants, such as central heating systems `for villas p and minorapartment houses, often a-combustion 210 of only 1-2 kg. oil per hour isnecessary. The present invention relates to a method of supplying the.fuel, whereby a particularly widerangedcontrol of the supplied quantityof fuel is made possible, and thelinvention'is characterized by the factthat the fuel is-sprayed into the combustion space intermittently or ina pnlsating mannenwthatis in an increasing and decreasing quantity.Besides the advantageof ehicientandtcomplete combustion, theeconomically L importantadvantage is gained-that the fuel `consumptioncorresponds with great accuracy to the actual yneed byregulating thesupply; for example by changing` the stroke of the pumping piston, whena supply pump is used. I When ,carrying` outthemethod, the fuel is,without the addition of air, supplied to one or several spraying nozzlesin such a Way that, when leaving the nozzlefit flowsin an intermittentcur- ,p rent or in a pulsating current with great variationsin quantity.i l 4 To obtainperfect combustion and a fully satisfactory 're withoutdanger of soot Y formation or extinguishingthe lire, itis found-`fthatcertain requirements'and data concerning `both the variations inpressure andrquantity of the liquid fuel as Well as the number ofsuchvariations per time unit must be observed.

By tests `made accordingly it has been proved 5 that the maximumpressureofthe oil in the burner should notivb'e lessA than V2atm.,,landthat thepressure should vary `between this lowestv maximum pressureand zero orsubstantially zero, and thatfthe number-of injections should be at least`lea'uslpreferably, 100,-,500 perminutedepending (Cl. 15S-117.5)

on the viscosity of the fuel, inflammability, and velocity of flamepropagation. Y

' vIn minor plants working with comparatively light burning,refinedoils,` 4 to 10 atmospheres may be adopted as a suitable maximumpressure 5? with 300-500 sprayings per minute.

According to the invention, however, botha higherfmaximum pressureandagreater number of` injections per minute than the above mentioned may beused. It is, however, of importance 10V to so adapt the number ofinjected charges per minutelthat the combustion `of any one fuelchargeiis not wholly completed kWhen the next charge is admitted. A

`When. using a pulsating current with great va- 15 riations it shouldbe-observed that the last mentioned `object is .attained in such a waythat the injected quantity of fuel decreases by at least 25-30%.andlWhenworkng with very small quantitiesof fuel .may even decrease by40-50% of the maximum. quantity, of fuel. In certain cases With small.plants Working with avery low fuel consumption per hour, l for exampleoil-fired minor central heating systems for villas, it has proved.convenient to work with so great varia- 25 tions of the injected fuelquantity as to 80% and even up to The injection of the fuel isconveniently carried out by means of an intermittently acting pumpwithout the interconnection of any device acting as an air vessel;However, the injection may also 30 be carried out in other ways forexampleby meansof a member, such .as a Valve, which is arranged in thespraying nozzle or the fuel supply conduit and adapted to openperiodically and 35 to close more or less. Y y

To obtain a perfectcombustion ofthe fueliinjected from .the sprayingnozzle as an intermittent or pulsating current, the fuel is suitablymixed with and finely divided ina continuously admitted air currentbefore the fuel reaches the combustion chamber.

To conduct the oil to the spraying nozzle it is suitable to use` apistonpump. It is then of particularly great importance that the connectingconduits between the pump and the nozzle beias non-yielding or unelasticas possiblaand itmust be. observed that .the conduits do not contain,any pocketslwhcrein air and gases mightaccumulate; Itfhas also beenproved that even thesmallest 5d of such accumulations acts asan airvessel and prevents the intermittent-.orstrongly pulsating injectionsfrom-taking place. ,Y

Other ,characteristics ofi .the invention will be moreclearlyset forthin fconnectionowiththe following description of the form of theinvention illustrated by way of example on the accompanying drawings.The drawings disclose a plant provided with pump, burner, air blower,electric motor and oil purifier.

Fig. 1 shows in longitudinal section an elevation of an injecting deviceaccording to the invention. Fig. 2 is an end view thereof, partly insection on the line II-II in Fig. 1. Fig. 3 shows a section on a largerscale along the same line through the pump and associated parts. Fig. 4shows a plan view of Fig. 3, and Fig. 5 shows in elevation a section online V-V of Fig. 4.

I is a mantle or housing, wherein an electrical motor 2 is mounted. Atone end of said housing a fan 3 is arranged, and at the other end agearing 4, 5 for operating the fuel oil pump 6 is mounted.

The fan 3 consists of a fan wheel 8 mounted on the shaft 'I of the motor2, whereby an air current is forced through the spiral-shaped fanhousing, past the burner nozzle 9 arranged at the end thereof andsurrounded by curved guides I for the air so that the latter is given arotating or whirling motion to be intimately intermingled with thefinely divided fuel injected by the nozzle 9. The fuel is admittedthrough the conduit II connected to the pressure side of the pump 6.

The pump itself consists of a cylinder I2 with a pump piston I3 therein.The piston is subjected to the action of a spring I4, which forces thepiston to accomplish its suction stroke, whereas the pressure stroke iselfected by means of a cam or eccentric disc mounted on the shaft I ofthe gear 5, said cam I8 acting on a lever Il pivotally journalled aboutthe pin I6. Said lever I'I bears against th-e back end of the pumppiston I3 between the pin I6 and the point of contact of the cam I8against the lever I'I. 'I'he pin I6 is mounted on the lower end of a rodI9, which is movably arranged in a sleeve 20 and subjected to the actionof a spring 2 I, which tends to maintain the rod I9 and, thus, the leverarm I'I in a raised position. The highest position of the rod I9 isdetermined by a pin 22 screwed into the upper end of the sleeve 2D,which pin can be adjusted manually or by means of a thermostat or thelike. The sleeve 20 is mounted perpendicularly to the pump piston and insuch a position in relation to the cam I8 that the lever arm II, whenswung to the position farthest away from the shaft I5, is perpendicularto the longitudinal axis of the pump piston.

By this device the pump piston, in all the control positions of the rodI9, is in a fully inserted position, whereby with safety any air presentis driven out and a regular suction of the fuel is insured. The fuel issucked from the oil-purifier 23 through the conduit 24 and is forcedinto the conduit 44, which is connected to the conduit II leading to theburner nozzle 9, and to the conduit 25, which latter conduit is closedoff by means of a bursting washer 26 and on the other side thereof,communicates with the suction conduit 24 by means of a channel 45 orwith the open air or directly with the fuel container. By thisarrangement the Ybursting of the conduit II is prevented in case thenozzle 9 should be filled up. The bursting washer must be practicallynonyielding, if the intermittent feeding of the fuel through the nozzleis to be maintained. The washer is therefore made with a very smalldiameter, for example 4-5 mm. 2l and 28 are the suction and exhaustvalves respectively of the pump. To prevent leakage of fuel oil past thepump piston I3, the pump cylinder I2 is provided with an annular channel29 about its central portion. This annular channel 29 communicates withthe suction conduit 24 through an additional channel 38.

The fuel supply to the oil purifier is effected through a supply conduit32 provided with a closing cock 3|. The Oil is admitted into thepurifier at the top through the conduit 33 and passes thence through thefilter 34 to the conduit 24, which forms the suction conduit of thepump. In the upper portion of the oil-purifier covered by a glass hood36, any air present in the oil is separated off, and this air is removedthrough the conduit 38 provided with a closing cock 3'I.

For the lubrication of the various bearings the gearing 4, 5 in theillustrated example is used as a gear driven pump, which obtainslubricating oil out of the well 39 and forces this through an axialboring 40 in the shaft 1, the bearings of the same and also through thechannels 4I and 42 to the shaft I5. 43 is a return conduit from the leftbearing of the shaft I to the well 39.

In a pumping plant of the present kind it is to be noted that evenapparently insignificant resiliency in the conduit may upset theintended result. This is clearly the case where we consider pistonstrokes of a length of only 0.2-5 mm. and a piston diameter of 6-10 mm.

The fuel injecting nozzle should be of such a character that the fuel isvery finely divided when injected into the furnace. To make the divisionmore or less ne, the nozzle may be controlled for example by means of adisplaceable rod screwed thereinto and connected with a sprayer body.

It is not necessary that the air be supplied by means of a fan orcompressor as illustrated. The air necessary for the combustion may beadmitted into the combustion chamber by a natural draught. Theadvantages connected with the intermittent or pulsating fuel supply aremaintained also in such a supply of the air of combustion.

The method and means according to the invention may, of course, be usedin connection with the now common automatic devices for igniting andextinguishing under control of one or several thermostats, which areinfluenced by the pressure or the temperature in the boiler 0r thetemperature in the fire-place etc. At the point of control of the fuelsupply, a regulation of the air of combustion should also take place.For this purpose one may in the illustrated arrangement cover thesuction opening of the fan by a rotatable valve 46 of a known character.As previously stated the pin 22 may be controlled by a thermostat andwhen this is the case the same thermostat may control the adjustment ofthe Valve 46 or an additional thermostat may be used for the latterpurpose.

Having now particularly described the nature of our invention and themanner of its operation, what we claim is:

l. The method of combusting liquid fuel in the combustion chamber of afurnace at substantially atmospheric pressure which includes the stepsof injecting the fuel into the combustion chamber in a pulsatingcurrent, mixing air therewith and igniting said mixture and Varying thequantity of fuel in said current per time unit, the current attainingits maximum from to 500 times, per minute.

2. The method of burning liquid fuel in the combustion chamber of afurnace which cornprises spraying a current of fuel into the chamber ata maximum pressure of 4 to 10 atmospheres, mixing air with said fuel,igniting said mixture and Varying said current from substantially 10% ofits maximum to a maximum and vice versa fromv 300 to 500 times perminute.

3. The method as claimed in claim 2, in which the air is supplied in acontinuous current which moves with the fuel into the combustionchamber.

4. The method of burning liquid fuel in the combustion chamber of afurnace which comprises injecting the fuel in a current of constantlyfluctuating content, mixing air with said fuel and igniting the mixturein the combustion chamber.

5. The method as claimed in claim 4 in which an increasing part of thefuel current reaches the combustion chamxber and mixes with air forcombustion while a decreasing part of the fuel current is still burning.

6. The process of burning liquid fuel in the combustion chamber of afurnace which comprises the steps of forcing the fuel as a spray intothe chamber, varying the flow of the fuel from a minimum to a maximum anumber of times of the order of 100 to 500 per minute, mixing air withsaid fuel and igniting said fuel in said combustion chamber.

7. The process of burning liquid fuel in a furnace which comprisespassing a continuous current of air into the furnace, spraying a currentof fuel into said current of air, mixing air with said fuel, ignitingsaid mixture, varying said current of fuel in the range of 1/2 kg. ofthe liquid fuel per hour, to 5 kg. of said fuel per hour, saidVariations taking place at the rate of 100 to 500 per minute.

8. A method of burning liquid fuel in a combustion chamber whichcomprises iiowing a current of air into the combustion chamber,impregnating said current with a spray of liquid fuel, igniting saidmixture, and varying the quantity of fuel sprayed from a maximum to aminimum of from 10 to 75% of said maximum, said Variations beingcontinuous and at the rate of from 100 to 500 per minute.

BROR HENNING LUNDBORG. OLOF' VALFRID TILLBERG.

